Heart failure is a degenerative disease that leads to decreased cardiac output that is highly symptomatic, with significant quality of life issues for the patient. Treatment beyond drugs includes cardiac resynchronization therapy (CRT), cardiac assist therapy such as LVAD (left ventricular assist device), and ultimately heart transplant. Resynchronization control of the left and right ventricles of the heart provided by CRT therapy in heart failure patients has proven benefits, including safety, improvements in quality of life, and reductions in hospitalization and NYHA Class heart failure levels. However, CRT therapy is only applicable to a subset of heart failure patients and a large percentage of heart failure patients who initially appear to be suitable for treatment with CRT therapy are “non-responders” to the demonstrated benefits. Less than 30% of heart failure patients are considered for CRT treatment and non-responders are reported to be 25% to 45% of patients treated.
A number of mechanical cardiac assist devices are used to treat heart failure patients. Such devices include both pulsatile devices that operate in timed synchrony with the heart and non-pulsatile devices that run without any such synchronization. For example, counter-pulsation heart assist devices such as those disclosed in the Applicants' U.S. Pat. No. 6,808,484, issued Oct. 26, 2004 and entitled “Heart Assist Devices, Systems and Methods,” which is hereby incorporated herein by reference in its entirety, are configured to compress the aorta in synchrony with the diastolic period, the beginning of which is marked by closure of the aortic valve to reduce the interior volume of the aorta during diastole. This compression increases systemic blood pressure, increases blood flow through the coronary arteries and increases diastolic output against the closed aortic valve. Release of the compression timed to the r wave and beginning of systole provides left ventricular unloading and improved native contractility of the heart muscle.
Other pulsatile heart assist devices include co-pulsation devices, which are configured to compress the heart in synchrony with the contraction of the ventricles or filling of the aorta. One example of a co-pulsation device is a right ventricular co-pulsation assist device, such as the devices described in U.S. Pat. No. 4,690,134 or U.S. Pat. No. 5,169,381. Co-pulsation devices are triggered in synchrony with the ventricular depolarization to assist the cardiac output. Co-pulsation assist devices have been described for both the left and right ventricles and reduced to practice in animal studies such as “Copulsation Balloon for Right Ventricular Assistance: Preliminary Trials;” Circulation, 99:2815-2818 (1999). As in counter-pulsation, the timing with the native rhythm must be precise for maximum effectiveness.
There is a need in the art for improved methods, devices, and systems for controlling the operation of a pulsatile heart assist device or controlling the operation of both a pulsatile heart device and an electrical therapy device (such as, for example, a CRT pacemaker) for various types of cardiac therapies.